92RS_Ttop

iTrader: (3)

I'm mostly done with rewiring the engine bay in my camaro, and have a question about the fusible links that go on the battery lug on the starter. I need to repair or replace them due to the heat from my headers melting part of the insulation. I'd really like to relocate them away from the headers and starter, but don't know if there is a need for them to be connected at that particular spot.

My options are:
1- move them directly to the positive terminal on the battery. I already have an extended post on the positive terminal for the secondary fuse box I added a while ago, so this is the easiest option.
2- move them to the battery lug in the secondary fuse box I added a while back. It gets power directly from the battery via an 18" AWG 4 wire, so it should be able to handle the additional load.
3- move them to the large charging lug in the back of the alternator
4- leave them on the starter and try reroute them somehow. This is really my last resort, and only if they absolutely can't be moved for some reason.

The engine is a 350 with shorty headers, not long tubes.

I appreciate any input/advice you guys/gals have.

sofakingdom

iTrader: (1)

Of all the places you propose, the only suitable one is #1.

OrangeBird

iTrader: (1)

I've gotta take issue with this suggestion , and here's why ;


A fusable link , as we all know , is a designed in "weak point" in the circuit and will open up in the event of overload . Now that we have stated the obvious , lets consider HOW that link will open . Most likely , in the event of overload , the link will appear outwardly melted (the insulation) and the wire itself will have burnt open . This opening of the wire under high current is HIGHLY likely to produce a SPARK at the instant it breaks the overloaded circuit .

And you plan to have this spark happening right next to the battery

Best plan is to either put the fusable links back on the starter where the general put them in the first place , or if you MUST relocate them , please keep in mind that right next to (or bolted to the battery itself) is a recipe for disaster and a properly wired (correct gauge wire for the anticipated load) remote terminal point , AWAY from the battery , is the safe bet here .

skinny z

Why not eliminate the fusible link altogether and provide a properly fused electrical circuit just like any other machine that has DC power supply?
Pull a wire from the positve battery terminal to a suitable location, it doesn't matter where provided that the distance and the gauge of the wire are appropriate, and proceed with your fusing from there. If properly done the main feed wire will never be overloaded as the individual branch circuits should all be protected for over current.
In all reality, the only wires that really need to go to the starter are the ones for the starter motor and the solenoid. The rest is OEM convenience really.
If you feel the need, but it's entirely uneccesary, you could add a fuse to the main feed circuit as well.
As for a location next to the battery...while I understand the prospect of a spark igniting the off-gassing that might occur around the battery (and this is something I'm very aware of when boosting a vehicle), it may not be as big a risk, as in probably none at all, when the links are eliminated (they're only fuses after all) and replaced with a sealed blade type fuse holder.

paulo57509

Have you considered putting the wire bundle in a short length of fire sleeve to protect it?

92RS_Ttop

iTrader: (3)

While I am aware of the potential dangers of sparks near the battery, I don't think a break in the fusible link would cause an exposed spark. The spark would be contained within the insulation of the wire, and not exposed to open air or and gasses from the battery. Although I suppose the a sudden, extreme overload could cause a complete melting if the insulation and an exposed spark, but at that point I think I would have a lot more problems to worry about.

I have also had the secondary fuse box mounted beside the battery for several years, and have seen other vehicles with the OEM fuse box near the battery, so I don't think this is as big of an issue as suggested.

92RS_Ttop

iTrader: (3)

I have already considered what you're suggesting, but am hesitant to do this for 2 reasons. 1- in every thread I have read about replacing fusible links on this and other forums it does not seem to be the recommended way to go about this. 2- I have no idea what the normal current draw is on these wires, so that makes it hard to determine the appropriate size fuse to use. Although, I have thought about simply looking up the max amp rating of the wire used in the fusible links and installing a fuse with a matching rating. I even have open slots in my secondary fuse box that I could use for this.

92RS_Ttop

iTrader: (3)

I had considered this as well, but rejected it because I need to replace or repair the existing fusible links due to heat damage and because the overall goal of this rewiring project is to clean up/eliminate/hide as much of the wiring in the engine bay as I possibly can. And since I need to cut and splice the wiring anyhow, I figured I might as well move it to a cooler/safer location while I was at it.

skinny z

Reason 1: That's mostly because the people dispensing the advice really shouldn't be
Reason 2: Those answers aren't difficult to find.

A fusible link is nothing more than what it's called: a fuse. And a poorly designed one at that. For whatever reason, at the time of their conception, the OEMs thought it was good idea. They also used lead in their metal working compounds and built cars with no seat belts. Times change.
For what it's worth, my Astro van has the fuse and relay box almost directly OVER the battery. Doesn't seem to pose much of a threat. Further to that, my 86 IROC-Z (RIP) had the relay for the fan installed beside the battery. Think about it.
At one time we used to have batteries with vents. We also had to store them on blocks of wood because the cases were so porous that they would self discharge due to the damp concrete floors that they were typically stored on. That's not the case with a modern battery.

As for fusing, here's general rule of thumb that you can go by:
12 gauge wire (AWG): 20 amps
14 : 15 amps
16 : 10 amps
18 : 5 amps (Personally I wouldn't use 18 gauge wire to wire any kind of power circuit other than perhaps the lights for my gauges. And I'd check the wattage of each lamp and do a calculation beforehand.)
However the best guideline is to design the circuit based on the power requirements of the device you're installing.
FYI: I've been designing and building automation equipment for the better part of a couple of decades. An automobile isn't any different than a robot or handling system that has a DC power source. Wires are made to carry a certain level of current. It's up to you to build the circuit to handle it and fuse it accordingly.
Now in defense to the OEMs and how their circuits are designed, keep in mind that the lead from the big lug on ther starter (besides being convenient) feeds more that one device. In typically feeds an entire fuse block or in a more modern vehicle, and entire buss network. You need to be certain that when replacing the fusible link altogether that you're not short changing the power needed to run whatever's downstream.

Let it be clear, I'm not saying it's OK to eliminate the fusible link. I AM saying it's OK to replace it with something suitable.
You want guaranteed protection? Take a 10 or 8 gauge wire from the starter lug, run it up to the firewall and install a 30 or 40 amp fuse. Then from there, run the wire to wherever you want your power distribution to be located.

skinny z

Like I said, the only wires that really need to go to the starter are for the starter motor (large) and starter solenoid (small). The rest is merely distribution. (This references our typical GM/3rd Gen circuitry).

GaryDoug

Nothing wrong with putting them near the battery. Every 4th gen LT1 car has them mounted there. They will work better there than anywhere near the exhaust where they will pick up heat and throw off the melting point.

skinny z

Does anyone know if they even use fusible links anymore? Seems to be an archaic way of circuit protection and I'd think that with today's sophisticated electronics, they'd be long gone. Maybe not though...

TKR Performance

iTrader: (1)

I had a fusible link issue on my '85 T/A, and when I installed my new battery cables and mini starter, I wound up using a large gauge wire (can't remember which one to be exact) from the starter to a self resetting 40 amp circuit breaker mounted to the firewall. It works, I learned that I had to insulate it from heat, but if anyone has a part number or a better option for using a large fuse, please let me know. I'd prefer to have a fuse box and a large fuse.

sofakingdom

iTrader: (1)

Fusible links are BY FAR the best way of providing protection in the places they are typically used.

They don't introduce extra connections, which with fuses of typical sizes we might use in cars, is where they always fail. There are, of course, large enough fuses to eliminate that problem, but I don't know of any waterproof holders for them.

ALOT of newer cars have them up by the battery. Jeeps for example, put their main distribution box for high-power stuff literally up against the batt, and a fusible link goes right straight from the battery terminal to its feed.

But I'm just an electrical engineer that designs electric systems for hospitals, and was a broadcast station engineer for several decades before that; I don't really know anything about electricity.

skinny z

The you would know that except for the point at which the fuse actually contacts the fuse holder there are as many connections for a fusible link in a circuit as there are for a fuse holder.
By the way, how many fusible limks were there in the last hospital circuit you designed and or were involved in? I really can't imagine having my engineer had me prints for a new control panel that says to reduce the size of the #10awg feed wire to #14 so as to provide over current protection. Cars are behind the curve I know but not too far behind.
Not to bust your chops Sofa, but seriously, the fusible link is an outdated and archaic way of providing over current protection and one that simply brings the end user into the shop to get his stuff repaired. About the only thing I can say about them in a positive sense is that they're relatively immune to the environment they're installed in. Because of that environmetal toughness, I'll grant them that much. Then again, a well researched fuse holder could provide that same quality.

TKR Performance

iTrader: (1)

I agree with putting things back the way they were, but my wiring was pretty messed up, so I would have had at least 4 environmental splices per wire, which increases resistance, and adds 4 points of failure and 4 points of entry for moisture for each wire. I'm an aircraft electronics tech in the Navy, and that would never fly at work. That's the reason I ran it to the breaker.

sofakingdom

iTrader: (1)

Precisely.

For the task at hand, they are the best way of going about it.

We don't use fuses AT ALL in hospitals, of any kind. Way too unreliable, too hard to restore power after a fault, too hard to coordinate. But also, wiring in hospitals is not subject to vibration, wide temperature swings, or moisture.

Pocket

iTrader: (24)

If you're just worried about where to gang them, use a power distribution block (power strip) from a mid 90's S10. Mount it anywhere

Check out maxi-fuses as a replacement. Several OEM and aftermarket mini-blocks can fill the need

skinny z

Fair enough. But I still think they're outdated. For what it's worth, any of the accesories I've added in the Camaro tap off the battery terminal and run to fuse holder mounted close by.



I wasn't referring to the power distribution and branch circuits but more to the equipment that's IN the hospital and runs the show. Control panels (large and small) are largely protected by fuses. Then again, as you point out, they aren't cars.

92RS_Ttop

iTrader: (3)

This was really my main concern. The large power wire from the alt ran to the little distribution block mounted on the passenger frame rail, while the smaller wire from the + terminal on the battery ran to the starter. I'd like to run both to the same distribution block and move the block from the passenger rail to right beside the battery. I don't think having both there will cause any issues with charging the battery, but was not entirely sure. I kinda figured that if Chevy ran them to separate points, there must be a reason for it. But after seeing what looks like a completely stock 92 RS at the junkyard yesterday with both wires run to the distribution block, I'm thinking I'll be fine.

I also pulled the fusible links from that car, cut several inches beyond the fusible link splices, so I'm just gonna replace the burned ones in my car with those.

92RS_Ttop

iTrader: (3)

Just another quick thought. Since the idea seems to be that fusible links are supposed to blow slowly to allow for brief current surges, wouldn't a circuit breaker be a more appropriate replacement than a fuse?

skinny z

As long as you don't short change the gauge of wire used and provide the necessary fusing for what ever's downstream in the circuit then yes, you'll be fine.
I find that the wire from the alternator can often benefit from going up a size or two. Especially if you've added a high output alternator. (Mines upgraded to a 8 awg from original 12 awg). Remenber that if you bring that wire to your terminal block (instead of the battery + terminal which I prefer), that the wire from the terminal block to the + post has to be at least that size too.
Just be sure that you use the proper crimping tool and crimp terminals to match the wire size and lug/screw it'll be attached to. I've seen a lot of jobs go south because of shoddy workmanship resulting from poor tooling or application.

92RS_Ttop

iTrader: (3)

Since I'm just running a stock alt, I'll probably just reroute the existing wires, shortening them as needed. As for the connections, I only crimp them enough to hold the end in place while I solder it. I always solder connections and cover with heat shrink tubing. I used to just crimp them years ago, but just had too many problems with them pulling out.

mantaguy

iTrader: (5)

FWIW,My 86 TA has a fusible link next to the Battery.(Factory)I read this statement above " And you plan to have this spark happening right next to the battery" and I have to disagree with the author

skinny z

The problem with soldering is it tends to work harden the connection and makes it brittle. The same reason the OEMs use a fine multi-strand wire as opposed to the more construction orientated coarse strand. Resistance to vibration and breakage. A lot of my critical installations exclude the use of solder and criming is mandantory. These are non-automotive applications mind you but the principles still apply. I know some people swear by soldering though but then again I don't expect them to have a $300 crimp tool in their tool box and have to use a dedicated crimp to get a certifiable connection.
Lately I've made the move to weather pack connectors for most of my automotive installations. That's all crimp technolgy too but there are still a lot of places in a car that need the old ring or fork terminals as well as butt splices.
Heat shrink is always a good idea.

NINÅ

Quote:

Originally Posted by 92RS_Ttop

seems to be that fusible links are supposed to blow slowly to allow for brief current surges

skinny z

Exactly. (Although I might have to disagree with your choice of a new thread title.)

92RS_Ttop

iTrader: (3)

Yeah, most of my crimps that pulled out were done using a large pair of vise-grips. I know that isn't what they are for, but I was a teenager at the time and that was all I had available to me. I later picked up one of those cheap, all-in-one crimped/cutter/stripper tools and while I did get better crimps with them, I still had a few pull out. Since then, I've been soldering and shrink wrapping all my connections and haven't had a problem since. And for what it's worth, I have noticed most of the OEM splices in the camaro's engine bay are crimped, soldered, and wrapped in duct tape.